Donald Trump ran for president promising to be tough on immigration. Five days after taking office, he ordered Washington to cut funding to so-called “sanctuary cities” that defy federal immigration orders.

Communities around the country are struggling to understand the order. Many wonder if disobeying the president will merely cost them funds for law enforcement. Or will it also cut money for critical programs, including education, clean water and public housing?

Typically, sanctuary jurisdictions ignore federal Immigration and Customs Enforcement (ICE) orders, such as requests to hold unauthorized immigrants — often people picked up for minor crimes who would otherwise be released — while ICE petitions a court to begin deportation proceedings. Police and prison officials in sanctuary jurisdictions sometimes also restrict the information they share with ICE.

Defenders of sanctuary policies argue that local police lack the resources to hold these people. They add that sharing information discourages interactions between immigrant communities and the police, which could undermine public safety.

Critics of sanctuary jurisdictions argue that they are too easy on suspected criminals and that they encourage people to enter the United States illegally. These critics often point to the murder of a San Francisco woman in 2015, allegedly by a man who had been deported five times and was at large because the city had not honored an ICE request to detain him.

The sanctuary debate pre-dates Trump’s election by decades. Today it hinges on a number of court decisions that give municipalities broad discretion over their interaction with federal officials. Since 2015, Congress has considered, but not passed, several bills that would restrict federal funds to sanctuary jurisdictions — of which there is no precise definition and thus no exact number (maybe a few hundred).

Here we outline the legal arguments, the budget implications, and the latest non-partisan research on sanctuary cities and the president’s promise to punish them.

Trump’s executive order

“Sanctuary jurisdictions across the United States willfully violate federal law in an attempt to shield aliens from removal from the United States. These jurisdictions have caused immeasurable harm to the American people and to the very fabric of our republic,” reads President Trump’s January 25, 2017, executive order 13768 (EO). “[J]urisdictions that willfully refuse to comply […] are not eligible to receive federal grants, except as deemed necessary for law enforcement purposes by the Attorney General or the Secretary [of Homeland Security].”

In response, the Congressional Research Service (CRS), a non-partisan government think tank working for Congress, issued a short brief on questions raised by the EO:

Since there is no legal definition of “sanctuary” jurisdictions, which communities are affected? (The Justice Department describes them in a 2016 memo as entities that fail to report “aliens in custody” to the federal government.)

Does “federal law” include “any federal statute or regulation or is [it] limited to federal immigration laws”?

The EO includes a caveat: “to the extent consistent with law.” The CRS notes in another brief that “it is unclear the degree to which this reference might limit the application of funding restrictions in particular contexts.”

Finally, which federal funds are affected? In a March 2017 brief, the CRS observes that the EO gives the Attorney General and the Secretary of Homeland Security discretion to decide which grants could be withheld: “A broad interpretation of ‘federal grant’ could include any federal grant outlay to designated sanctuary jurisdictions regardless of which federal agency administers the grant program. A more narrow interpretation of the definition of ‘federal grant’ could limit the affected grant programs to those programs directly administered by the Attorney General and the Secretary” – i.e. law enforcement and border security programs funded by the Justice Department and the Department of Homeland Security (DHS).

As we discuss below, several Supreme Court rulings suggest that the federal government cannot link immigration to funding for unrelated programs. Nevertheless, some municipalities fear, and are preparing for, a fight.

Challenges

There are over 11 million unauthorized immigrants in the U.S., according to government statistics. The Pew Research Center estimates that more than half live in just 20 major metropolitan areas, such as New York, San Francisco, Chicago and Boston.

As the essence of Trump’s plan became clear after his election victory, cities began vowing to resist. The mayor of Somerville, Massachusetts, for example, issued a defiant statement in November 2016 declaring his Boston suburb a “sanctuary city.”

“How much federal funding could we lose? A lot. Currently Somerville receives approximately $6 million in recurring federal funds per year for things like special education, school lunch programs, substance abuse prevention, and homeland security. That constitutes about 3 percent of our annual budget. Additional grants for programs such as housing are also sought each year. If we lose this funding, we will tighten our belts, but we will not sell our community values short.”

After Trump’s EO, residents of the neighboring town of Arlington – population roughly 43,000 – began debating whether to declare their community a sanctuary. In a fact sheet, town authorities say that of the last 1,000 criminal arrests (over an unspecified period), “only one had an immigration detainer, and in this instance, federal officials chose not to pursue it.” The town receives no federal police funding, but it does collect roughly $4.5 million in federal grants annually (about 3 percent of its budget) for education and low-income residents. The fact sheet acknowledges that the Trump administration could try to cut these funding sources.

Washington D.C., stands to lose up to 25 percent of its budget if the EO is applied, according to a Washington Postcalculation that estimates New York City could lose 9 percent.

A January 2017 Reuters analysis found the nation’s 10 largest cities could lose $2.27 billion annually in federal funds if the executive order succeeds: “Among the funds at risk are $460 million that the federal government gave out to fund Head Start pre-school programs in the 10 largest ‘sanctuary cities’ in the most recent fiscal year, the analysis found. Washington also sent $238 million to municipalities to fund airport improvements and $153 million for HIV prevention and relief.”

Within days of the EO, several cities had filed lawsuits challenging it as unconstitutional, including Chelsea and Lawrence, Massachusetts, and San Francisco, arguing that the order violates the Fifth Amendment for being vague and the Tenth Amendment for “commandeering” a local government.

The National Conference of State Legislators has detailed several of the arguments communities could use if they defy or sue the Trump administration:

A 1987 Supreme Court ruling (Dakota v. Dole) limited Congress’s ability to set conditions that are not “germane” or “related to” the purpose of a federal grant. Withholding education spending, for example, is unlikely to qualify as germane to an immigration order.

Cities could also argue that the EO is “coercive.” The Supreme Court ruled coercion unconstitutional in 2012 when it struck down theMedicaid expansion provision of President Obama’s health care law, arguing that forcing states to accept the expansion in order to receive federal funding amounted to a “gun to the head.” That would, manyhaveargued, violate Congress’s Constitutional spending powers.

The Supreme Court has interpreted the 10th Amendment, which defines states’ rights, to prohibit the federal government from “commandeering” state powers or requiring state or local governments “to enact or administer a federal regulatory program.”

Federal grants

If the Trump administration manages to overcome the legal obstacles to shutting off funding to sanctuary communities, most of that funding will be discretionary — assistance to states and local governments that is administered through federal agencies such as the Department of Agriculture or the Department of Housing and Urban Development (HUD). The government’s Catalog of Federal Domestic Assistance describes 2,308 federal programs and provides contact information for the agencies that award the funding, which can come in the form of grants. The grants are often managed by state or local governments or other local groups. (For more on how the federal budget process works, check out our explainer.)

A March 2017 report from the Congressional Research Service describes federal grants and how they are awarded. It estimates that in fiscal year 2017 grants to state and local governments exceed $596 billion. Total outlay data by program is available from the Office of Management and Budget. State and local governments often publish figures for how much they receive from each program, but so far most have been left guessing what they might lose.

Immigrants and crime: Mostly rumors

Critics of open immigration policies and sanctuary cities often claim that immigrants breed crime. But extensive research tends to prove the opposite. For example:

A 2014 paper in the Journal of Law and Economics investigated Secure Communities, a federal program between 2008 and 2014 that automatically transmitted arrest data to immigration authorities, who could check the immigration status of any detainee. (This is the kind of federal program that sanctuary cities oppose — refusing, for example, to hold non-violent detainees after they have been processed.) The paper found “no observable effect” on crime rates in the cities where the program was implemented.

Another 2014 paper, this time in the journal Criminology and Public Policy, found a similar lack of impact on crime from the Secure Communities program. It also found that critics of the program had little reason to fear it would enable discriminatory policing.

A 2012 paper in the Annals of the American Academy of Political and Social Science found that immigrant communities in Chicago experienced lower levels of crime than average; in Los Angeles, these communities were prone to higher levels of crime. The authors speculate that characteristics specific to Los Angeles may help explain why it is an outlier. The article begins with a review of studies showing that neighborhoods with high numbers of immigrants experience lower-than-average crime levels in general.

A forthcoming paper by scholars at Highline College and the University of California Riverside found no association between sanctuary jurisdictions and rates of violent crime or property crime.

Other resources:

For background on immigration law, Cornell Law School has a useful overview.